Enable tests to non-main branch

Author: dstansby

.github/workflows/test.yml

@@ -7,7 +7,7 @@ on:
   push:
     branches: [ main ]
   pull_request:
-    branches: [ main ]
+    branches: [ main, "docs/3.0-user-guide" ]
   workflow_dispatch:
 
 concurrency:
@@ -111,4 +111,4 @@ jobs:
           contains(needs.*.result, 'cancelled')
         run: exit 1
       - name: Success
-        run: echo Success!
+        run: echo Success!